Semiconductor device and method for manufacturing the same

A semiconductor device comprising:

• a first semiconductor region containing silicon carbide;
• a second semiconductor region provided on the first semiconductor region, the second semiconductor region containing silicon carbide of a first conductivity type;
• a third semiconductor region provided on the second semiconductor region, the third semiconductor region containing silicon carbide of a second conductivity type;
• a fourth semiconductor region provided on the third semiconductor region, the fourth semiconductor region containing silicon carbide of the first conductivity type;
• a control electrode provided in a trench, the trench formed in the fourth semiconductor region, the third semiconductor region, and the second semiconductor region;
• and
• an insulating film provided at a first position and at a second position, the first position being between a side surface of the trench and the control electrode, the second position being between a bottom surface of the trench and the control electrode,
• the insulating film including a high-dielectric constant region and a bottom portion insulating region,
• the bottom portion insulating region being provided between the bottom surface of the trench and the control electrode,
• the high-dielectric constant region contacting the third semiconductor region, the high-dielectric constant region having a higher dielectric constant than a dielectric constant of silicon oxide,
• the high-dielectric constant region including a first insulating region and a second insulating region, the first insulating region being provided between the side surface of the trench and the control electrode, the second insulating region being provided between the first insulating region and the third semiconductor region,
• a dielectric constant of the first insulating region being higher than a dielectric constant of the second insulating region,
• the dielectric constant of the first insulating region being higher than a dielectric constant of the bottom portion insulating region.